/* fact written for the Unix/Linux 'bc' basic calculator */
/* run using bc < fact.bc */

define rfact(n) {
  if (n==0) return (1);
  return (n * rfact(n-1));
}

define ifact(n) {
  m=1;
  while (n > 0) m *= n--;
  return (m);
}

define tfact(n,m) {
  if (n==0) return (m);
  m *= n--;
  return (tfact(n,m));
}

define fact(n) {
   return (tfact(n,1));
}


fact(10)
fact(11)
fact(12)
fact(13)
fact(100)
fact(1000)
fact(10000)